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How is vertical speed managed in Airliners?
When an Airplane starts to take off, the Horizontal velocity would generate it the necessary lift, and then Airplane pitches up to further increase the lift. As the Airplane is climbing up, the net vertical force on it should be the difference of lift and its own weight. When there is a resultant force, should not the climb rate be ever increasing? And when the Airplane reaches the desired height, I'm assuming - either the horizontal velocity is decreased or Airplane goes to normal state from Pitch-up position, basically balancing the lift with own weight. At this moment, Airplane has some vertical speed right, So Isn't the Airplane supposed to be climbing up with a constant velocity, even after reaching desired rate, as Objects continue to move in the same velocity when there exists no force on them? How is this managed in Airliners?

"Isn't the Airplane supposed to be climbing up with a constant velocity, [...] as Objects continue to move in the same velocity when there exists no force on them?" Lift and drag, thrust and weight are acting. Vertical speed (acceleration) can be cancelled varying lift factors: Angle of attack and speed. If speed is fixed, there is a possibility to change the angle of attack to adjust VS, and thrust to keep airspeed constant (or vice-versa, depending on the theory you prefer). See this for a start.

The stop to the climb as speed increases comes from changing the pitch of the elevator or stabilator, which controls the angle of the wing. Want to climb less? Raise the tail so the wing angle changes and creates less lift. Doesn't take much. Then use elevator/stabilator trim to hold it there after the desired speed is reached.  Similar to reaching highway speed in a car - step on the gas to get to 65, then back off to hold it, step on it a little more to get up a hill and hold the speed, back off a little going down a hill and not accelerate wildly like an 18-wheeler gaining momentum.

Vertical speed is managed, primarily, with controls.
Lift is proportional to square of speed and to angle of attack¹ and angle of attack can be adjusted using the elevators. Pilot, or automation, use those to control the flight path of the aircraft.
As the aircraft accelerates along the runway, at some point the pilot pulls on the control column, which turns the elevators up and the resulting downforce on the tail lifts the nose off the ground². That increases the angle of attack—because the aircraft is still moving horizontally—, lift exceeds weight and the aircraft accelerates upwards.
As it starts to accelerate upwards, the pilot eases the pull on the control column to prevent the aircraft pitching up further. And as the aircraft accelerates upward, the angle between direction it is flying and pitch—that is the angle of attack³—decreases again, until the forces get in balance. Then the aircraft is in steady climb.
When the aircraft reaches the top of climb, the pilot⁴ pushes on the control column. This causes the aircraft to pitch down, which reduces the angle of attack, and thus lift, and the aircraft starts to accelerate downward, that is slow down the climb. At the point the aircraft is moving horizontally, the control column is pushed back to get the forces back in balance.
Now for the details of operating the controls, the longitudinal stability comes into play. Aircraft are normally⁷ designed to be longitudinally stable. That means the aircraft will pitch up as its angle of attack decreases—which increases it again—and pitch down as its angle of attack increases—which decreases it again. Net result is that when the elevators are left alone, the aircraft will maintain specific angle of attack.
As the aircraft climbs, it will tend to slow down unless engine power is increased, because its potential energy increases and it will be taken from kinetic energy if the engines are not providing enough⁸. And as it will slow down, its lift will decrease, so its angle of attack will increase, but that will cause it to pitch down due to stability. The net result is that it will refuse to climb unless enough power is provided.
Similarly when it descends, it will tend to accelerate, because the potential energy will be converted to kinetic⁹ and that will increase lift, which will decrease the angle of attack and the stability will make the plane pitch up. So it will refuse to descent unless power is reduced.
So in the end, vertical speed is actually managed by thrust levers. Which is also much more easily proven from law of conservation of energy.

¹ Up to critical angle of attack, where stall occurs.
² This is called rotation.
³ Angle of attack is properly defined as angle between the relative wind and the chord line of the wing, but aircraft axis is often used in practice. This makes things simpler as you don't have to consider the angle of incidence—angle between the aircraft axis and wing chord—especially since many aircraft have twisted wings where the angle of incidence changes along the span.
⁴ Or more often the autopilot. While take-off is always flown manually, up above FL290⁵ use of autopilot is required as it gets too tiring and unreliable to maintain the altitude by hand with enough precision to ensure separation⁶.
⁵ Flight levels are defined by pressure corresponding to given altitude, in hundreds of feet, on a standard day. So FL290 is 29,000 ft, but more when it is warm and less when it is cold. The reason is that pressure can be measured easily and quite accurately and flying at sufficiently different pressures ensures the altitudes are also different.
⁶ Originally the minimum separation was 2,000 ft above 29,000 ft due to the lower accuracy of altimeters and lower accuracy of flying as the aircraft move faster in the thinner air up there. But because all the aircraft wouldn't fit up there with those separations, 1,000 ft was allowed provided the aircraft is flying on autopilot and has sufficiently accurate altimeter. This is called reduced vertical separation minima
⁷ Some fighters are intentionally designed as unstable, because it allows faster control response. All such aircraft have computerized controls that compensate this, otherwise it would be very tiring to fly.
⁸ Alternatively, consider that the lift vector is tilted aft, and thus has bigger aft component, which is drag. Physics always has multiple ways to analyse a situation.
⁹ The lift vector is tilted forward in descent, so there is some forward component that accelerates the aircraft.

The end of the question sounds like he's asking about momentum, i.e. if lift/thrust exert a constant force while climbing, and gravity and drag are roughly constant, why doesn't the plane keep accelerating upward? Also, when you level off, why doesn't momentum keep you climbing even after the four forces are equalized?

@StephenS, the answer is looong, because I wasn't sure what is the actual point of confusion, but I still do believe I did address this point.

My gut tells me the (small) vertical momentum is somehow canceled by drag, but I am not quite seeing how to get there from your (excellent) discussion of pitch and lift.

No, the vertical momentum is cancelled by moving the controls so that the lift is less than weight until all the vertical momentum is removed. That's what the fifth paragraph describes.

I see it now, thanks!

@StephenS in atmosphere, if an accelerating force is removed drag will slow movement to a stop in that direction.  Same as when you make a banked turn.  Vectors really help here.  Picture rounding out from a climb.  Lift now = weight (throttle is pulled back too).  Drag will quickly lower the vertical velocity component.  And so will gravity! It is rare to exactly level out perfectly straight, but as one rounds with elevator, reduces throttle, and trims for cruise at that altitude, they are operating the air craft as Jan says.

@RobertDiGiovanni, drag is, by definition, the component along the relative wind, and therefore has nothing to do with this. Changes in flight path angle are due to changes in lift, the fact that both forces are part of the same physical phenomenon notwithstanding. Lift equals weight during steady climb (not really, it is a bit less, because there is also a component of thrust acting against weight), but it is strictly less when leveling off.

@Jan Hudec I recognize your experience here, but we went though this in detail before.  A climbing aircraft has a vertical drag component.  Tell me a rocket is not using thrust to overcome gravity AND drag at a given velocity!  I was concerned people would think somehow AOA decreases in a climb.  Don't need power on stalls, do we?  Must monitor airspeed, and control it with pitch!  But I do delight in the discussion, and greatly appreciate what I learn here.

@Jan Hudec  We look at the same thing a little differently sometimes.  I take gravity as the universal reference force vector.  Anything opposite is "lift". Considering "lift" as a perpendicular force relative to the aircraft only makes sense in discussion of the wing, but relative to the discussion of the complete aircraft all vertical components (including thrust and drag) need be considered.

The real concern, even though we do momentarily increase AOA during rotation, is the mindset that increasing AOA will make us "climb" while taking off.  Far better is to think "adding speed increases Iift".  Much safer.

@RobertDiGiovanni, a climbing aircraft does, indeed, have a vertical drag component. It is, however, parallel with the flight path (by definition; the parallel component is called drag and the perpendicular component is called lift), so it can't change that flight path.

@RobertDiGiovanni, I also don't agree that it ever makes sense to define lift as the vertical component. Besides being contrary to the standard definition, it makes things harder to analyse, not easier.

@Jan Hudec ok, so (one way of seeing it)  relative to the gravity vector is the vertical drag component of the climbing aircraft.  In translating the physics into SOPs for pilots (that are safe) I only hope to stress the importance of maintaining airspeed.  Sort of like "hey, it's ok to increase your AOA to climb, as long as your airspeed is good".  In reality, as we rotate to lift off, the plane continues to accelerate to Vy.  The angle of climb at safe air speed depends on how much "rocket" we are.  Thanks and good day!

I find it helps to look at the force vectors:

(source: own work)
The left shows the forces conventionally, with the plane at the center.  However, if we rearrange them as on the right, we can see that the forces are balanced.  This means the plane is in unaccelerated flight.
If we pitch up to climb, this is what happens:
]
(source: own work)
The thrust, lift and drag vectors rotate with the plane, but gravity still points downward.  On the right, we can see that the forces are no longer balanced, so the plane accelerates upward.
If we do nothing else to compensate:

(source: own work)
At left, the plane slows down, which will reduce lift and drag. The forces now balance, and the plane returns to unaccelerated flight.
At center, we complete our climb and pitch back down.  However, the forces are again unbalanced, so the plane accelerates downward.
At right, the plane speeds up, which increases lift and drag. The forces now balance, and the plane returns to unaccelerated flight.
If we also adjust thrust, the results are slightly different:

(source: own work)
At left, we increase thrust to maintain speed, which will keep drag the same, but lift still decreases. The forces now balance, and the plane returns to unaccelerated flight.
At center, we complete our climb and pitch back down.  However, the forces are again unbalanced, so the plane accelerates downward.
At right, we reduce thrust to maintain speed, which will keep drag the same, and lift increases.  The forces now balance, and the plane returns to unaccelerated flight.
Summary: While there is acceleration at the top and bottom of the climb, there isn't during the climb itself, so vertical speed remains constant.

Here is a timeline of an airplane taking off and climbing to cruise:

The airplane does its takeoff roll. During this phase, the upward force on the aircraft is equal to the weight of the aircraft. The vertical speed is zero. Initially, all of the upward force is produced by the landing gear.
The airplane pitches up and begins a climb. During this phase (which lasts only a few seconds), the upward force is greater than the weight. The vertical speed is increasing.
The airplane climbs steadily. During this phase, the upward force is approximately equal to the weight again. The vertical speed is positive, approximately constant.
The airplane levels off. During this phase, the upward force is less than the weight. The vertical speed is decreasing.
The airplane cruises at a constant altitude. During this phase, the upward force is equal to the weight. The vertical speed is zero.

To answer your specific questions:

When there is a resultant force, should not the climb rate be ever increasing?

That's right; as long as the upward force is greater than the weight. However, as long as an airplane's vertical speed is increasing, its angle of attack will automatically decrease, even if it maintains a constant pitch. So in practice, any time that the upward force is greater than the weight, it will quickly go back down until it's approximately equal to the weight again.

And when the Airplane reaches the desired height, I'm assuming - either the horizontal velocity is decreased or Airplane goes to normal state from Pitch-up position, ...

This part is correct. Generally, when the pilots decide that they're done climbing, they'll pitch down in order to stop the climb.

... basically balancing the lift with own weight.

This part is not correct. During the climb, upward force and weight are already balanced. The way that the pilots stop the climb is by temporarily making the upward force less than the weight.
I don't think pilots usually think about upward force and weight; the thought process is more like "I want to climb, so I'll pitch up" and "I want to stop climbing, so I'll pitch down". But "behind the scenes", what they're really doing is adjusting the upward force.
(You'll notice that I'm saying "upward force" instead of "lift". For the purposes of this topic, the difference isn't important, but there is a difference.)

At this moment, Airplane has some vertical speed right, So Isn't the Airplane supposed to be climbing up with a constant velocity, even after reaching desired rate, as Objects continue to move in the same velocity when there exists no force on them?

Your reasoning is correct. If the pilots want to keep the vertical speed constant, they will keep upward force equal to weight. When they want to start climbing, they'll make upward force greater than weight, and when they want to stop climbing, they'll make the upward force less than the weight.

"Accelerate wildly like an 18 wheeler gaining momentum"? Now hold on there, just a second.
The crux of this question is balancing of forces.  In atmosphere drag is what prevents any object from continuously accelerating.  Drag will increase with velocity until its force is the same as the accelerating force.  Now you have balanced forces at constant velocity.
Easiest example is the parachute.  Without one your terminal velocity will be around 120 mph falling prone with arms and legs out.  Even faster if you point straight down (less drag).
The parachute provides much more drag, and requires only 15 mph to balance gravitational
acceleration.
In 18 wheelers, we try to control our speed with dynamic braking (from engine) to avoid heating brakes.  We also know doubling speed will heat brakes 4x faster as kinetic energy is
proportional to the square of velocity.  Also of note is the stopping distance is 4x greater as well.  Speed control also serves one well in landing as the same kinetic energy will square with velocity.  At 70 mph you have 36% more energy than at 60mph.

The je ne sais quoi of climb out is to hold Vy with pitch at full power.  Watch that airspeed!


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Approach speed Exceedance
What are the possible effects when an aircraft exceeds its approach speed limitations? i.e. unstable approach? Go around? Runway overrun I know a lot of factors come into play, however, I wish to determine the worst possible scenario

What limitations are you thinking of? As approach speed is normally based on aircraft mass, there isn’t a fixed upper limit on approach speed per se. Other limits come into play, for example flap limit speeds etc.

lets assume an aircraft has an approach speed of 200kts during final, the AFM indicates it should be 185kts- in FDA this deviation is recorded as a Red event - however landing is uneventful. What are the possible risks involved in this instance...i hope you understand

"What happens if an aircraft lands too fast", is that basically what you are trying to ask?

@MarshallinoCoetzee In this case, I don’t believe 185 kts is an aircraft limit in true sense. For FDA, each operator has to agree on operational limits for event identification, in my company e.g. this is done in increments of 10 kts for most speed targets. The risks associated with exceeding these operational limits have to be identified performing a risk analysis. For approach speed, provided no AFM/AMM limits are exceeded, the risks to the aircraft are mainly centred around landing and stopping performance on the runway or, vice versa, the unfavourable outcome could be a runway excursion.

@CptReynolds in my company for example we do not alter the FDA parameters. the application we use is AirFASE and we use the default parameters build into the FAP for the specific aircraft/ fleet. Thanks for the help. It makes sense that stopping performance would be affected based on the RWY length for example, and RWY excursion would be the worst possible outcome if the brakes do not give n prior to this, then again if the high speed approach is not corrected, hard braking would be the next possible event trigger in FDA? Thanks again for the assistance!!

@ben exactly my phrasing was a little off. LOL

http://enroute.aircanada.com/en/articles/are-there-speed-limits-for-aircraft

@MarshallinoCoetzee I don’t believe we have a “hard braking” trigger, as hard braking may well be quite right in some cases. What I would trigger for on landing is “long flare/late touchdown” (e.g. distance/time from 50ft to weight on wheels), “high speed at touchdown” (based on difference from normal ops or standard procedures), “high speed at stop end” (i.e. xx kts with less than yy meters LDA remaining) and potentially things like “late deceleration” or similar, although that is in itself another contributor to runway excursion risk not to do with approach speed.

@Cpt Reynolds i have seen a parameter "questionable breaking at landing" i guess this would have nothing to do with the high appr speeds? Thanks again for the information shared

If for example the high appr speed event is airport specific can the flow of traffic by ATC attribute to the event in FDA? I also interpret the aircraft FCOM SOPs which we have adopted, as saying it is acceptable as long as the speed slows down to the managed speed??

@MarshallinoCoetzee I would argue that if high approach speed event is regularly triggered by ATC speed restrictions (e.g. 160kts to 4DME as in LHR), the event trigger needs to change to reflect the normal operational environment - unless of course there is a company procedure to not adhere to that ATC instruction...

@MarshallinoCoetzee I don’t think „questionable braking“ has much to do with approach speed; however I am not certain. My gut feel is it’s rather too little braking than too much, but I really don’t know; we don’t have that trigger - at least not under this description. I hope you don’t mind, but can I please observe I‘d recommend to rename it using an objective description of what it triggers on, rather than the word „questionable“ which could be construed to imply judgement passed on flight crew action?

@CptReynolds modifying the event trigger would then encompass all operations...the event is only specific to a certain airport where traffic is high, esp during our slot times, thus i do not think modifying the parameter is recommended...? Upon further investigation I realized it is our smaller fleet which have this problem upon landing and mainly due to ATC request for an earlier turn off during taxi... unfortunately i am not allowed for "you to observe" - company policy - I trust you understand. The comments, however, have given me a broader understanding. Thank you indeed!

@MarshallinoCoetzee Oh, I didn’t mean I wanted to see any data or so - it’s just a figure of speech. My fault. I only wanted to recommend the renaming!

@CptReynolds no worries. thank you in any case for sharing your knowledge and undoubted experience. Rgrds

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Why are the positive points in a V-n diagram associated with pitch maneuvers?

For an aircraft with such flight envelope, the flight conditions in point A, C and D are associated with symmetrical pitch maneuvers. So, for the combination of loads factor n and speed V in each of those points represents a symmetrical pitch maneuver, in which there is a certain angle of attack and certain deflexion of the elevator, both different from zero - all other control surfaces wouldn't be deflected. That comes from reports from SAE aero design competition and from Structural Loads Analysis: Theory and Practice, Lomax
I understand the airplane can execute any maneuver so long it is inside the flight envelope, but why are the critical pitch maneuvers those "described" by points A, C and D whereas critical rolling or yawing maneuvers have clearer definitions* regarding the most extreme conditions related to those maneuvers?
*Here's an example from Lomax (nothing like that is said from symmetrical pitch maneuvers)

Two types  of yawing maneuvers,  as  shown schematically  in  Fig.
  4.1,  must  be considered  for structural design...

Because they are reached when the aircraft flies a pitch maneuver. Let's look at the three points in detail:

Point A: This is where the highest turn rate can be achieved, so it is reached normally in an attempt to change direction. You might argue correctly that this is not a clean pitch-up, but essentially it is. When starting the turn, the aircraft will deflect both aileron and rudder, but once the turn is steady, both will essentially be neutral, except for the small deflection needed to overcome damping effects. What is left is a pitch maneuver akin to a loop with mostly elevator deflection to pull the needed gs.
Point C: This is reached inadvertently when flying into a heavy gust. Aircraft fly straight for most of the time, especially when flying fast, so it is assumed that this happens in straight and steady flight. Here, not even an elevator deflection is needed to reach the envelope point, all you need to do is to fly through exceptionally turbulent weather.
Point D: This is only reached after the pilot screwed up. Certification rules like JAR 23.335 b(4)i explain what the authorities assume: The pilot went into a shallow dive when upsetting the controls, oversped the plane and now tries to slow down by pulling up. This will also most likely occur in symmetric flight only. Or maybe in the initial phase of a dogfight, but then different regulations apply.

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How to determine the maximum servo torque required for a nose gear?
It's pretty much it. I know how to calculate the friction force on the nose gear for a three-point landing condition using the method set forth in Structural Loads Analysis for Commercial Transport Aircraft Theory and Practice, by Lomax. To calculate the torque I am looking for, would I just take the cross product between the friction and the radius of the nose gear?

These may be related: Chapter 7 - Landing gear and How much force does a 747 land with?

Assuming that we are designing a steering system, for a single steering wheel aircraft.
The servo is yawing the wheel to a position. The position causes side force on the wheel. And that generates a yawing moment for the aircraft. (The aircraft can be moving in various directions, but assume you know the max side force required.)
This side force, multiplied with the distance of the wheel contact point and the wheel yawing axis is one major contributor to the servo torque. (Torque1)
Another contributor is the rotational friction of the wheel. Which is the resistance to yawing further. (Torque2)
Torque_total = torque1 + torque2.
This is the output torque for the servo mechanism. The mechanism will affect the torque on the servo shaft.

Can you further explain the Torque 1, please?

I’ve come across this image that depicts the landing gear: https://goo.gl/images/Mvyu7T


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Where can you join a STAR & STAR Altitudes?
Do you have to join a STAR at a transition or can you join it at any point?
For example, coming from the south, can I join the DODJE5 arrival at FZT rather than AEX?
DODJE5: https://aeronav.faa.gov/d-tpp/1908/06918DODJE.PDF
Also, if I were to fly this in a standard GA prop aircraft, would the MEA looking numbers (ex. 5,000 for FZT -> CQY) be required?

You can only file, and ATC can only assign, one of the listed transitions. However, that doesn't mean you will actually fly it as charted (unless you lose comms). If you filed lower than the charted altitudes, you are not expected to climb. In practice, ATC mau give you direct a later fix (e.g. FZT) where you'll join aircraft descending to your level. Or, if you're slow, they might put you on vectors off the STAR to keep you out of the way of faster traffic. It all depends on what else is going on around you, so it's difficult to predict what will actually happen.


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How to find the measurement of how far Tail plane to Center of gravity of the aircraft?
How do you find the measurement of Piper Archer Tail Plane distance to the center of the gravity.
Google really doesn't help me... maybe you guys know some website that has databases of small aircraft.
Thank you very much and best regards,

As you know the CG position varies with loads carried. The limits are explained at §2.13 of the POH page 26, (this figure page 94 can help too)

First you calculate the position of the CG, then you do a simple arithmetic calculation based on the station of the tailplane.

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What were the safety recommendations following the Aeroperú Flight 603 crash?
I just watched the Mayday Air Crash Investigation about Aeroperú Flight 603 and two questions that weren't answered are:

Who was responsible What caused the ATC to relay false altitude information to the pilots
Has anything changed since then to prevent that from happening again?

I'm trying desperately to find a suitable answer to your point 1. Can I ask you to clarify. Do you know that they relayed false information, or are you actually asking "Was ATC in any way responsible for this accident?". That I can answer from the official reports.

@Jamiec The altitude information ATC relayed back was what the plane itself reported to ATC. Neither the pilots nor the controller appeared to realize this. So I wonder if it was bad training or bad user interface design.

Yes I got that. Have you read the english traslation of the ATC transcript by any chance? The controller was just reading back what they saw on their screen along the lines of "Yes, we have you at 4000ft". Anyway I think you have an answer to the "cause" which was the source of the controllers info. See @stelios' answer.

@Jamiec My question is why didn't the controller realize that the altitude was what the plane reported and not from radar trigonometry as ratchet freak answered below. Maybe he wasn't properly trained to know this, or maybe the UI on his own screen needed a redesign to make it clear where the data comes from. ("The Design of Everyday Things" by Don Norman has more examples of user interface failures that may be of interest.)

The radar system would need to be equipped to read the altitude from it. They werent at that facility. And as I have updated in my answer the controller had no reason to believe the altitude was incorrect. There's no UI failure here AFAICT

@jamiec Well, the pilots had told ATC their altimeters had failed. Presumably if the UI was clear that the data was coming from the plane, ATC wouldn't have believed it (or at least been suspicious).

I believe that for point 1 that both ATC and pilot assumed the height information on the ATC radar display came from radar trigonometry and not the reply of the transponder. Neither was at fault here and this is more likely due to bad training on both sides.
If either had realized where the altitude information came from then the mode C transponder would have been deactivated and if the radar station tracking them was equipped with to do altitude triangulation then the ATC could have provided better altitude information.
Incidentally with GPS being more common nowadays it can serve as a backup altitude indicator.

who was responsible for ATC relaying false altitude information to the pilots

Not an easy question mostly because it asks (even if not directly) to put the blame on someone. And although there is not an explicit rule for not doing this, I prefer avoiding it in respect to the dead and the ATCOs doing their job as good as they can.
I will focus on the reason behind the "false reports" and not the responsibilities. The RADAR system the ATCOs use relies on aircraft systems for two things: one is to identify the flight (Mode A) and the other is to get its altitude in hundreds of feet (Mode C).
Now if you recall what happened, the static ports were duct taped for some routine cleaning of the fuselage and were not removed. This affected the airplane's altitude indicator and consequently the altitude transmitted by Mode C.
So the ATCO was reporting back to the plane the same erroneous altitude the pilots were seeing in the cockpit.

has anything changed since then to prevent that from happening again?

I don't know if there was any action taken after the accident but I think that there wasn't anyone needed: there is regulation (need to make some research to find it) which specifies that all "foreign" parts attached to a plane for protecting its vital parts should have a prominent red "REMOVE BEFORE FLIGHT" ribbon.
The duct tape was of silver non reflective color (if I recall correctly) and had no ribbons. When the crew inspected the plane at night with flashlights they couldn't spot them.

Independent of plane systems- ATC should be able give accurate information. It would a mystery why they didn't think wouldn't be important.

@user2617804 No actually ATC gives only the information they have. And not all information is accurate since they rely on 3rd parties in acquiring them. There are vertical scanning radars that can provide altitude information but are rare for civil use and their accuracy reduces with range. And they don't really help preventing accidents

What caused the ATC to pass incorrect information to the flight crew was that they had no reason to mistrust their own instruments. The altitude information displayed to the controller was transmitted from the aircraft itself, and at the time the controller was no more aware of the issue on board the aircraft than the flight crew were.
The NTSB, although not the investigating authority did produce a short report which noted that:

Section 12-25-01 of the Boeing 757 Maintenance Manual contains the instruction for cleaning and
  polishing the airplane. When preparing the airplane for cleaning and polishing, maintenance
  personnel are instructed to prepare the airplane by taping moisture-resistant paper over the static
  ports to prevent the entry of any contaminant

The safety advice which came from this was:

Immediately review and amend, as necessary, all airplane maintenance manuals
  to require operators to use only standardized, highly conspicuous covers with
  warning flags attached in any situation in which static ports would need to be
  covered.

Ultimately the crash was caused by failure of the maintenance crew to remove the static port tape, failure of the flight crew to spot this defect on inspection. (The following quotes are from here).

It can be deduced from the investigation carried out that the maintenance staff did
  not remove the protective adhesive tape from the static ports. This tape was not
  detected during the various phases of the aircraft's release to the line mechanic, its
  transfer to the passenger boarding apron and, lastly, the inspection by the crew
  responsible for the flight (the walk-around or pre-flight check), which was carried
  out by the pilot-in-command

Together with failure of the flight crew to respond appropriately to the ground proximity warning system.

The pilot-in-command [...] made a
  personal error by not complying with the procedure for GPWS alarms and not
  noticing the readings of the radio altimeters in order to discard everything which he
  believed to be fictitious

And furthermore

The co-pilot [...] made a personal error by not
  being more insistent, assertive and convincing in alerting the pilot-in-command
  much more emphatically to the ground proximity alarms.

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Where did the 22NM come from in acceptable VOR signal on a MOCA? Why 22NM?
SO a MOCA provides ROC along entire route but acceptable VOR nav signal for only 22NM.  Why 22NM?

Just a comment: 22NM is just a little above 40km. Maybe someone used 40km, converted to nautical miles, and then rounded to the higher number.

Shielding by terrain?

Looks suspiciously like 25 statute miles to me, which would be a very typical distance increment back when VORs were first deployed (by 1946, see: https://en.wikipedia.org/wiki/VHF_omnidirectional_range).


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How the antenna on the B737 Max fuselage doesn't disrupt the airflow?
As the title already say, how does the antenna on the Boeing 737 Max fuselage not disrupt the airflow?
(Boeing) 737 MAX antenna.

Edited to make your question more understandable. Please read How do I ask a good question? for some more details on how to post a good question on this site.

Which antenna? Are you talking about the satellite antenna that is added (not shown in that picture)?

Welcome to aviation.SE! Somewhat related. A picture would be really useful here: aircraft have lots of different antennae and it isn't clear if you mean one specific antenna, or all of them together?

Anything new attached to the outside of the airplane will change the airflow in someway; that is unavoidable.
The only question is if it will disrupt the airflow in a way that has a significant negative impact on the plane.
You'll recognize that the antenna is installed very close to the CG, so the new air resistance has virtually no pitching moment.
It is far from any control surface, so those all work the same.
The increased air resistance affects fuel economy a very tiny amount, but paying customers have enough preference for inflight wifi that its worth it.

Do you think it could be a safety issue?

What kind of safety issue?


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What is this propeller found underwater in the English Channel?

I need some help identifying this piece.

It would help if you gave some measurements, identifying numbers, etc. From the picture it is a twisted-up 3 blade prop which were pretty common. Whoever was at the other end of that thing probably had a really bad day.

Given the rust on the hub, I really really doubt any numbers or text will be legible. You probably won't even see where the text used to be...

looks like a smallish variable pitch, constant speed, metal propeller that's been in the water for not all that long (or has had a lot of corrosion cleaned away already).

Based on the fact that the blades remain mostly straight, it was probably not under power when it hit the water.

The asker never came back to give clarifying information such as size, so I'm voting to close as unclear.

My best guess is that propeller is related to the 19 June 1954 – Swissair Convair CV-240 flight which was ditched in the English Channel near Folkestone due to fuel exhaustion. As @AEhere mentioned earlier it looks like the propeller wasn't under power.
the propeller shape look similar but still the size of the propeller being provided in the photo relatively small compared to the actual aircraft propeller.
Sources :
Wikipedia:https://en.wikipedia.org/wiki/List_of_accidents_and_incidents_involving_airliners_in_the_United_Kingdom
http://www.sr692.com/fleet/15_cv240/index.html

The square tips on the Convair propeller look quite different to the one round tip on the prop in the photo.

@PeterKämpf I‘d add sizes don’t seem right, either


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If the the body and it's wing is mostly covered with solar panels and flies with electric motors, is it possible for that aircraft to fly?
First before I say anything else, this is indeed a stupid question.
It would be most likely heavy, bulky, and expensive.
But theoretically, is it possible to fly with only Solar energy?
What does it take to accomplish such task? The total cost? Probable shape and size? The power required to lift off such a stupid aircraft?
What does it take to lift off with a single average man piloting the solar-powered aircraft? Without a man?
If you did calculate the amount of power needed, for both lifting a man and not lifting anything but itself, what else could you used that energy for?

Have you see this manned plane? Battery power to help with takeoff, solar after that. There was even a Nova show on PBS about it recently.  https://www.theguardian.com/environment/2016/jul/26/solar-impulse-plane-makes-history-completing-round-the-world-trip

Do gliders count? Technically they fly with atmospheric airflows created by solar power.

I believe Facebook is flying one or such planes. They are in the air 24 7.  They provide Internet access to remote areas but the goal is to provide global Internet access.  They have the wingspan of a 747.  They charge their batteries during the day using solar on their body and wings and use that solar to power the aircraft and equipment during the day.  At night the batteries take over

As a technology demonstrator, certainly, but not for practical transportation of goods or people. The energy available in sunlight, (~1000 watts/sq meter), even if 100% efficient, is not sufficient to provide enough power to push an aircraft through the air at the speeds necessary to make it useful. An aircraft that can only achieve 20 or 30 mph with a cargo capacity of a few hundred pounds is not going to replace hydrocarbon fueled aircraft.

Not a stupid question at all! This was one of the goals that solar impulse I and II set out to show. one thing to keep in mind is that its of course only possible while the sun is shining. It was able to do it but the margin of error was fairly small,

During the day, the plane flies only by the energy from the sun. But
  in the morning and evening, when sunshine is not so strong, and
  especially at night, it must tap into its reserve of energy stored in
  its batteries. So every evening, the pilot must make sure that the
  plane’s batteries are 100% charged so that it can fly until the next
  sunrise.

Solar impulse ran on 8HP motors which is not much more than the Wrights first powered aircraft with a cruise speed of 56MPH it was not a terribly fast aircraft either but proved the concept was possible at a small edge of the spectrum.

Several designs show that solar powered flight is possible. The actual design pretty much depends on the requirements. Solar Impulse 2 is maybe the most famous aircraft, but possible not ready for everday use. The Solar Impulse design resulted from the goal to fly around the earth and especially to be able to fly through the night, based on batteries that are recharged during the day. If you don't need the sustained flight over night, you can come up with other solutions. A pretty good example is the Sunseeker Duo.
The power required for level flight can be estimated by the product of total drag and airspeed. The drag itself can be estimated using aircraft weight and lift over drag ratio.
This is why solar aircraft are very similar or even based on gliders, as they are designed for minimum drag as well as low weight.
To get an idea on the electric power and energy required to get a powered glider from the ground you might also have a look at the Lange Aircraft or the Front Electric Sustainer () propulsion concept.


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How is maximum payload determined in the payload-range diagram?
What determines the maximum payload weight, as seen in the horizontal line of a payload-range diagram? I understand that
$ OEW + W_{fuel} + W_{payload} \leq MTOW$
but what's stopping me from just putting in 10lbs of fuel, enough to taxi across the apron, and therefore have a maximum payload weight of MTOW - OEW?

Aircraft also have a Maximum Zero-Fuel Weight (MZFW). This defines the aircraft's maximum weight without any fuel loaded. A large aircraft certainly would not be able to fly with only 10lb of fuel on board,
so structures like the fuselage are designed to carry a lower payload.
For example, the Boeing 777F freighter has a maximum takeoff weight of 347,814kg. The type certificate lists the MZFW as 248,115kg, which leaves almost 100,000kg for fuel out of the max fuel capacity of 145,538kg. This is a large increase from the passenger version (777-200LR), which has a MZFW of 209,106kg with only slightly lower MTOW.
See also: What are different types of weights of an aircraft?


text:
Need Airbus A380 model in .xml format
i am looking for Airbus A380 aircraft model in xml language/ format. Can anyone provide? Or share the xml code?

'xml' is not a format for describing 3D models. Even if this were possible, you would need much more information about how the data is stored than just saying "it's XML'.

Do you mean VRML?

There are community sites that create and share 3D software models of just about anything, including planes. Here is one for the A380, found by Googling. I can't vouch for its accuracy or correctness.
If this link breaks then you can search the same site for other postings, or for other similar sites.

Please don’t post link only answers, without the link this answer isn’t much use.

@Notts90 Exactly what are you expecting in answer to this, other than a link to the thing the questioner asked for? The actual file is far too big to be uploaded to the answer.

I don’t expect this question to be answered (it’s now closed). Even if it wasn’t closed as unclear it would be off topic as it can only really be answered with a link, which isn’t a good fit for this site as links rot.

Here’s the meta https://meta.stackexchange.com/q/8231/335608

And here https://meta.stackexchange.com/q/7515/335608

Rules are good, but they have exceptions. If the question is "where do I find this on the web" then the answer is going to fundamentally be a link. What the meta says is "Linking is not a bad thing as long as you actually provide some context to your answer.  At the very least you could explain where the link goes and what it is going to show the user." Check and check.


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How do airlines choose what food to serve?
I'd imagine there are probably reasons behind the choice of food that airlines serve, and I'm wondering what those reasons are?
I guess that Air India probably serves more curries than American Airlines, but what other considerations are taken into account? Presumably weight is one.

cheaply mass produced would be primary factor

Hot food doesn't need to taste as fresh.

it's all about airline catering and wikipedia's entry has more to tell about it

Interesting article: Asiana and Turkish Airlines latest carriers to introduce inflight chefs

1. Money
Meals are available at different prices. Most US airlines know you aren't choosing them on the basis of cuisine and pick the lowest priced meal they can get away with. Other airlines eg Emirates, Singapore compete by offering high customer services and so invest more money in better food and service.
2. Culture
Airlines which are mostly flying a home market will adapt the food to the traditions of the country. EL-AL aren't going to be serving bacon cheese-burgers and Air India used to do very good veggie curries.

Many international airlines tend to cater their meals to the destination pairs for a specific flight. So for example KLM will serve halal food on flights to Arab countries, Indonesian food on flights to Asia, etc. etc.


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Why shouldn't you inflate your life vest until you're outside the airplane?
On commercial flights, in part of the pre-flight safety demonstration, you're told in the event of a crash, not to inflate your life vest until you're outside the airplane — why is this?

Step 8: if it gets dark, apply lipstick.

Steps 1-9: Men shouldn't bother to survive at all.

Step 7: hold your hands out, and get ready to win the gold for diving.

Note: I noticed that some airline recently changed the rules: do not inflate if you exit in the wing emergency exit. IMHO unnecessary complication.

Ethiopian Airlines Flight 961 was the flight that resulted in this addition to the safety briefing.
After being hijacked, the plane eventually crash-landed in the ocean. Many passengers died because they inflated their life jackets in the cabin, causing them to be trapped inside by the rising water.
Mayday/Air Crash Investigation S03E13 (Ocean Landing) covered the incident. The relevant clip is here (from 23 seconds in):

Yup!  This is what I was gonna answer with!  BAD IDEA!

Also, don't deploy the liferaft/slide until the door is open.  Same reason.

Strangely I don't remember the flight attendant to actually stress that point when they demonstrated use of the life vests in the cases I've seen.

@JanHudec I recall them always saying "do not inflate your lifejacket until you're outside of the aircraft".

@JanHudec:  When you're flying an over-land domestic flight (say, ORD to LAS), they'll barely mention it.  When flying LAX to SYD, they will emphasize it.

Your youtube video has broken because of author right issues

In addition to the risk of being trapped mentioned by Danny Beckett, the overwing exits are small.  If you inflate your vest before exiting, you'll have a harder time getting out, and you're more likely to tear the vest.

That's exactly the same reason. You're trapped because you can't fit through the doors with the vest inflated :)

@jwenting: I'd say that Danny's answer suggests the buoyancy is what causes problems with getting out (certainly the screengrab shows this). It might be the same ultimate reason but from a different direction but it isn't something mentioned by Danny that I can see.

@jwenting No. The point in Danny's answer is that, as the plane fills with water, you may need to swim under it to get to the door. That's impossible (by design) when wearing a life jacket.

The main reason not to inflate prior to hitting the water & getting out is that most likely the person would need to swim under water to get out and with Ethiopian Airlines Crash, a lot more people actually survived the impact with the water, but because they inflated their life vests before the crash, the vest pushed the people to the top of the plane, thus making it impossible to swim out. One would think that if someone is fighting for their life and had inflated they would push up on the vest and try to push themselves down to get it off, but I think once inflated, the vest is fairly snug, which may make pulling it off by pushing up & forcing your body down hard to accomplish. Plus with injuries, even harder. I just think a lot of people on planes are older or have children traveling w them or can't swim, which complicates matters even more. All I know is that after watching "Aircrash Disasters" that from now on when I fly, I'm bringing 1) spare life vest (to inflate - not put on) to use as a cushion in the event of impact. 2) leather coat - a mid to long length one (in the event of fire, leather protects the body to a degree - plus sharp debris etc) 3) sit in the back of the plane.  If you look at the majority of survivable plane crashes, most of the survivors are usually seated 1) over the wing, which is the most structurally stable part of the plane (strongest part) - plus, emergency door is usually above the wing, but it's a double edge sword because the fuel is stored in the wings! So fire could get ya! Explosions etc. 2) Back of the airplane / tail section: in quite a few survivable crashes - the only survivors were at the back of the plane - such as the Japan Airlines crash into the mountains of Japan - over 500 people died. Main reason is because Japan refused the help of the us military that had a nearby base & found the crash site 1st. Japan sent a military helicopter & the pilot "assumed" there were no survivors because he didn't see people moving about. Which is nuts! Because after a crash that bad, are people supposed to be jumping up & down? the Japanese military waited until the following day to go to the site (plus they didn't have night vision equipment) and were shocked to find 4 survivors - the survivors were all women all seated in the back of the plane - the tail snapped off & was flug away from the fire/ main crash site. All of the survivors reported that they heard people screaming & crying out in pain and for help. I just can't believe Japan waited until the next day to send anyone to the crash site and let those poor people die. Over what? Not wanting the help of the us military? Everyone else (other countries) seem to gladly take the help of the us. Seems senseless to me. But anyways - back of plane is the safest spot in the plane in my overall opinion. Leather coats, blankets, pillows/anything that can serve as a cushion all can help increase survival/injury rate. The only other thing that can be a huge help is a smoke hood - but we won't see those on planes because it was deemed that smoke hoods would slow people down on evacuating due to the fact people would stop to put the hood on instead of just immediately trying to get out of the plane. Maybe we should just buy our own hoods & in the event of a firery crash throw the hood on while bolting to an exit door! Lol

This answer could be improved by breaking it up into paragraphs, and removing unrelated topics like the Japan Airlines crash.

Almost no one dies from being burned in fires. They're usually dead of smoke inhalation before fire ever reaches them, so that leather coat isn't going to be of much use.


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What noises can you hear as a passenger?
I'm just curious as to what the noises are that you can hear as a passenger in the cabin of an airliner?
For example (ignore the crew talking), the noise at 7:09 - 7:30 on this video; is that the flaps?
What other sounds might a passenger be able to spot?

+1 I'm especially interested in barking below the passenger cabin of A319 when leaving/arriving a gate.

...and on the same type, why is there somebody in the hold sawing through the main spar?  Or at least, that what it sounds like.  Or is that my interpretation of the same barking noise?  I did ask an FO once as he walked down the cabin and muttered something about hydraulics like he had a vague idea but didn't really know.

@tohecz: The "barking" is the "barking dog pump", or power transfer unit. It pressurizes the two main hydraulic systems (green and yellow) from each other. It briefly runs when the first engine is started.

@Jan.  I've heard the guy sawing furiously after engine shut down.  Also sometimes during gate delays before start.   Ah ha, I've just read the link for the PTU.  It states A320 but I'm sure that it's on the A319 also.  I guess it's the same basic design.

@Simon: You are right. The yellow system has electric pump, but green does not. So whenever left engine is not running and green system is used, the PTU runs.

@Jan thanks.  That's good info.

How is this too broad?  And who on earth is flagging two year old questions?  Voting to leave open.

At that point it was indeed the flaps extending in preparation of takeoff (you can see them moving through the rain).
You would typically also be able to hear the cargo doors closing (before the plane starts taxiing) and the engines ramping up as you start to take off (at 8:54 in the same video).

I don't suppose you can find a YouTube clip where you can hear the cargo doors closing? Thanks for your answer btw!

you also can hear the gear extension/retraction

You can also hear whine (or barking) of  electric hydraulic pumps in some airplanes.

@casey: The "barking", at least on Airbus, is the PTU, which is hydraulically powered hydraulic pump.

There are loads of noises you might hear; there are fuel pumps, hydraulic pumps, air circulation, adjustment screws, servos, and on Airbus aircraft a strange clanking noise when you go over bumps in the tarmac.
On the ground you may hear (and feel) cargo pallets rolling on the hold, and the hold doors being opened and shut. In-flight you have engine noises and air flow noises.

An interesting noise you can hear is the sound of the PTU (Power Transfer Unit) during the A320 startup. It sounds like a cross between a dog barking and someone dragging a wet finger across glass.
https://www.youtube.com/watch?v=9aGsXmNjPRw
What happens is that the PTU is transfering pressure from one hydraulics system to the other to equalize them. Since the pressure is not always unequal between the hydraulics systems, this is not audible during every startup.

A major noise (and vibration) during the flight is the retraction and extension of the landing gear as well as the wheel brake on the wheels once the gear is fully retracted. The vibration is more noticeable (obviously) on aircraft with the main gear in the fuselage and if you are seated over the main gear.


text:
Do planes have keys?
One thing I've always wondered is: do airplanes have keys that you put in the ignition to start?
And on the outside doors? Otherwise how are they secured and started?
I'm interested to know about a broad range of aircraft; from GA, all the way to airliners.

At one point buses in London did not have keys, but they had two starter buttons that needed to be pressed at the same time, the button were arranged so a child could not reach both at the same time.

Even if there is a key for the ignition switch, it's not necessarily required for running the plane. If you get the engine running by turning the propeller, it could just keep running on its own. Planes are mainly designed to keep themselves running in the air at all costs, and safety trumps security.

@200_success , I've never seen a key that turned on the starter but not the magnetos. You would need those on to start the engine.

@Jungroth A propeller can be hand-started.

@200_success I know that, I've done it many times. I also know that for the engine to run, it needs to have the magnetos hot. And I'll say again, I have never seen a GA airplane that required a key for the ignition, but not the magnetos. Therefore, you wouldn't be able to prop an airplane that needs a key to start. What you could do is open the cowl, disconnect the p-leads on the magnetos, and hand prop the airplane. But at that point, you're really just "hotwiring".

Related (...in space!)

The DA-42 has a key for turning on the starters, but since it is FADEC all you really need is Engine Master On (ie. electrical power) and windmilling the prop will start the engines w/out a key. On a side-note, I always wondered why a 60.000Euro Ferrari has an impressive key, while the key for a 800.000Euro aircraft looks like a cheap 0.35$ lock.

Presumablly because plane theft has never become a big problem the way car theft has.

Small planes tend to have keys, but not all.  The bigger the plane the less likely a key is needed and once you get into jets, I can't think of any that need keys for engine starts.  The starting and securing of engines with no keys comes down to switches and knobs.
Likewise with exterior doors, on smaller planes including private end executive jets, you can find keyed exterior doors and luggage compartments.  With transport jets at airlines you won't find keys. To secure those doors the jet bridge is pulled away from the airplane so there is no physical access to the boarding door.

Theoretically then, if someone broke into an airport and stole a mobile staircase, what's stopping them from getting into an airliner?

@DannyBeckett nothing but the knowledge of how to operate the airplane and perhaps an astute local controller who would alert the police to the unexpected movement of the aircraft.

@DannyBeckett theoretically, if someone stole the key, what's stopping them from stealing a small plane? That's essentially the same question. "If someone can get past the security system in place, what's stopping them?"

@DannyBeckett also, there are examples of people stealing airliners. Typically it's by pilots who already have some amount of access and certainly the knowledge to operate the aircraft.

@BretCopeland That's remarkable! A key would have stopped that...

@DannyBeckett I think you grossly overestimate the quality of aircraft keys/locks. I could pick the typical Bendix keyswitch for mags with a paperclip. As for the door - well the hinges for the Cherokee's door are on the outside which shows you how much of a security measure the door locks are :)

So essentially, a fueled plane is just sitting around for someone to get into the cockpit and take off with it? I know it is not as trivial as it sounds: you still need to know how to fly a plane and go through ATC, but that's about it?

@BobbyAlexander; well, that, but there's also this thing called airport security where these types of aircraft are sitting, with fences, gates, and guards. If you get through those, I don't think a lock on the plane would provide much extra security.

@DannyBeckett You're gonna get some hop ons..

My (Cessna 182) has a key. If I lock the door and take the key with me, a dedicated thief could break in with very little damage, and I suspect the ignition switch could be easily broken with a large screwdriver. At least my hangar door is slightly more difficult to force open (requiring bolt cutters). Fortunately, theft in aviation is pretty minimal.

Shortly after 9/11 there was a student pilot who stole a light plane (I think he got the entry key from the office) and deliberately crashed it into a building. I also recall a story about an aircraft cleaning crew who were fooling around in the cockpit and managed to release the parking brake and maybe even start an engine, causing some damage to the aircraft and terminal as the plane rolled forward.

@mah Not condoning aircraft theft, but if your ignition switch ever dies take a look behind the panel: the keyswitch is just a couple of wires leading to ground (all it does is ground the P-lead of each magneto). Cut or unplug those wires and the mags are hot.

This was covered more than 10 years ago in a Belgian television show that got quite a bit of attention. It's in Dutch but the images should speak for itself.
Two people dress up as pilots and find their way in the Brussels (Zaventem) airport using social engineering. They actually manage to enter the cockpit of an airliner, which requires no keys to start.
You can watch the video of this here:
http://www.een.be/programmas/de-generatieshow/90-bart-en-tom-dringen-de-luchthaven-binnen
The reasoning is that airport security should suffice. Obviously this security was not without its flaws.

Entering the cockpit of a parked plane, and flying it away are two different things.

@rbp true for the general public, not very true to the aviation community.

As I said in another answer, there are lots of planes that can't just be flown away, even by a pilot, unless he knows that type.

@voretaq7 my airplane has a Medeco!

Well you also have to think about what the point of the theft is. We already have a recorded instance of a maintenance crew stealing a plane, then subsequently crashing it. If death or jail is not your goal, stealing a plane don't really get you anything else. You can't easily fence it, and going to another country most likely will give you the same results.

As a private pilot, single-engine land, I've flown maybe fifty different light planes--none with any more than four seats or 210HP--and all of them have had ignition keys.  I haven't been in the cockpit of anything bigger.
Generally the keys have five positions: OFF, MAG 1, MAG 2, BOTH, and START.  You insert the key at the OFF position, turn it all the way to START and hold it there until the engine catches, and then release it back to BOTH.  MAG 1 and MAG 2 (sometimes LEFT and RIGHT) are for the runup check just before takeoff to make sure both your magnetos are working.
Usually the same key that fits in the ignition switch fits in the door lock.  It's pretty common for a small plane to have only one door that's unlockable from the outside: you lock all the other doors from the inside, then climb out and lock the last door.
One thing I've noticed, though, is that keys and locks for small planes don't appear to be serious--at least, not the same level of serious that you see on cars and buildings.  They're more serious than briefcase keys or computer-case keys, but they look about as pickable as a cheap padlock...and while I've never looked, I wouldn't be surprised if you could reach under the edge of the instrument panel, pull wires with spade lugs off the back of the ignition switch, and touch them together yourself.

As voretaq7 pointed out, you likely won't even need to touch them together.

Private aircraft tend to be parked at airports with no effective security, and owned by individuals who expect to start and lock it like a car. I've seen many, and they all had ignition keys. Small aircraft (mainly single-engine) are also more-or-less interchangeable - if you can fly a Cessna you can fly a Beechcraft without any real issues so theft is a genuine concern.
Commercial aircraft are typically parked at large airports with 24-hour security, these days likely armed. And they are not interchangeable. Put a 747 captain with 20 years experience in Boeings into an Airbus 320 and he won't be able to find the light switch, never mind fly it away.

Besides ignition keys, small airplanes (single engine land) can be equipped with throttle locks. These metal devices fit over the throttle lever or vernier control and are secured with either a key or a numeric code.
I've frequently seen this kind of lock on rental aircraft.
Here's an example:

C-160 TRANSALL has a door lock. As a military cargo aircraft sometimes lands at remote airfields (or not even airfields), this is needed to "secure" the aircraft.

Heavy jet aircraft do not have keys. You can enter the cockpit door which do not have locks, start up the APU - a small jet engine in the tail - to give you power and air. Then start the main engines all of which just have toggle or push button switches. It would be very easy to steal if you knew the systems.
As an aircraft mechanic for 40 years I feel there is a severe threat for this to happen. I invented a small tool that would keep this from happening but no one is interested as of yet. There is a pilot who attempted to steal a commerial aircraft on 7-17-2012. I have contacted the TSA, FAA, Professional Pilots ass. with my concerns and the answer to the issue. I guess it will just have to happen before anyone listens!

After 911, passenger jets had hardened cockpit doors installed that cannot be opened in flight unless the pilot lets them in. The doors that I installed also had substantial locks on them. Before 911, the cockpit doors had flimsy latches, with a lock and key, that were designed to break a shear pin to unlock the door in case of rapid cabin depressurization. That tiny little shear pin also allowed the door to be easily kicked open. Maybe cargo jets don't lock their doors on the ground, and certainly don't need to keep passengers out. If it is a security concern, it should be addressed.

can you provide a link to the device you invented?

VINDICATION!!!!

Turn off the transponder, CVR, TCAS and takeoff at night without lights... only problem will be the tower will be on the phone with FAA/US MIL before you can get off the ground. And they'll be tracking you on primary radar unless you can fly at 100' or get below mountains. Odds of getting away are a snowball's. File a flight plan tor "maintenance" under an assumed name might work.

I think the answer is: it depends.
The Citabria has two toggle switches, one for each magneto, and a push button starter. Pilots who have never started one may have trouble because the accepted practice is to put the stick in the crook of your right elbow to keep the elevator back and the tail wheel on the ground, and your right hand on the throttle, which is on the left wall. After flicking on the mags with your left hand high on the right wall, you press the starter button with your left hand. It requires some practice! But I think it might confuse a Cessna driver, or at least make him nose over. Here's a picture of the interior of the LSA version of the Citabria:

My Mooney has a fancy high-security lock. But even if you have the key, the 270HP engine, turbocharger, and laminar flow wings, not to mention the constant speed prop, cowl flaps, and high V-speeds will prevent even a  777-typed ATP from having a successful solo first flight.

I'm pretty sure a 777 pilot can handle 270HP, dude ;)

I'm pretty sure a 777 pilot is used to laminar flow wings on aircraft... ;-)

I can only speak to types I have experience with, so:  Light GA singles typically have ignition keys.  Light GA twins typically do not.  When you get to the heavy stuff, I have no idea.  :-)

I suspect the "disappearance" of keys on (piston) multi-engine aircraft has something to do with the fact that you'd need multiple keys and ignition switches (one for each engine, to control the magnetos on that engine). Much easier with "regular" switches or knobs than to have to fumble for keys...

Some business jets like the Gulfstream for instance have a key to lock your passenger door from the outside, for instance if your aircraft is in night halt or you're gonna leave the aircraft parked for a day or so... it's mainly for the security of the aircraft.
Most commercially used aircraft like Airbuses, have a CDSS (Cockpit Door Surveillance System), which allows the flight crew to see who is trying to access the cockpit door from the cabin. Most of the time, a cockpit door with CDSS has a unique password to be entered on the touchpad of the cockpit door (at the entrance to the cockpit from the cabin) to get access to the flight crew compartment. These passwords are normally known to the cabin crew and flight crews only.
Commercial aircraft normally do not have a door key to lock it from the outside as its security is monitored by airport security staff.


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How do you quantify rudder effectiveness as a function of bank angle?
I'm currently reviewing just for fun aircraft dynamics based on OEI (one engine inoperative) scenarios. After reading that "lower pedal forces at higher bank angles" are required, it got me thinking into how different could the applied rudder forces be in two different test cases:

Loss of left engine --> need rudder to move to the right
Loss of right engine --> need rudder to move to the left

For all intents and purposes, let's assume that both 1) and 2) cases come with an aircraft that is at the same bank angle (right wing tip higher than left wing tip).
Ultimately, in which case, 1) or 2), would the rudder deflection need to be larger? Hence, which case would require higher pedal forces?

Normally the right engine-only (left engine failed) case requires more rudder input to correct for asymmetric thrust than the left engine-only because propeller P factor results in more rudder effectiveness when flying on the left engine (the net thrust line of the left engine, being offset to the right of the propeller disc, is closer to the rudder so the rudder has less work to do, and farther from the rudder on the right side so it has more work to do).
Unless the engine has counter-rotating propellers, in which case P factor effects are symmetrical, so the rudder requirements are the same in an engine-out situation.
Beyond that, in a twin with wing mounted engines generally, to achieve coordinated flight you bank slightly into the live engine (normally 5 degrees bank into the live engine is rule of thumb used for multi-engine training).
The reason you bank is that the thrust from the live engine, summed with the lateral thrust from the rudder application, causes a resultant thrust line that is skewed toward the dead engine, and you fly slightly sideways with the wings level.  Banking into the live engine introduces a sideslip component in the opposite direction, toward the live engine, realigning the resultant thrust line back to (more or less) straight ahead.
The result is the airplane is flying slightly banked, but straight through the air, that is, no sideslip even though the live engine wing side is down a bit. The skid ball will be pointing to the center of the earth but that location of the ball in the vial is toward the low wing (the ball should be about half a ball width off center toward the live engine).
Basically, the sideslip is cancelling out the lateral thrust caused by the rudder displacement, or conversely, the rudder input is countering the sideslip tendency from the slight bank being applied.
You can bank more than that, and it will require even less rudder, but you will now be side slipping toward the live engine and if you are in a light twin on a hot day with a lot of junk on board, you won't be climbing until you get things corrected.
So more rudder displacement is required, all things being equal, when the "critical" engine has failed, usually the left one if the engines both rotate the same direction, clockwise from behind.  If the engines are counter-rotating, like on a Lockheed P-38, or the Piper twins that had that feature, there is no critical engine and the displacements and forces are the same for either engine, although you still should be banking slightly into the live engine to maintain true coordinated flight.
On jets with fuselage mounted engines, this banking toward the live engine isn't required and is not taught, I expect because the amount of bank required is only a degrees or two, not enough to bother with.

Boeing does teach the use of a slight bank towards the operating engine. I believe Airbus does as well. Here is a quote from the Boeing 777  Flight Crew Training Manual: “When the rudder is trimmed to level the control wheel, the airplane maintains heading. A small amount of bank toward the operating engine may be noticeable on the bank indicator. The slip/skid indicator is displaced slightly toward the operating engine.”

Ah thanks!  I wondered about that.  I was trained on the CRJs and I expect the tail mounted engines made it less important, even though you still get a pretty hard yaw when single engine at TO thrust.  Probably the bank angle required is only 2 degrees, not enough to bother with.


text:
Semi-circular rule for choosing a FL: Risk of head on collision with borderline headings (179, 359)?
If it happens that you fly a 179/359 heading in uncontrolled airspace, what's the risk of collision with aircraft flying in opposite direction?

The adoption of semi circular rules is not meant to prevent collisions on its own. Rather, it is one of several safety nets contributing to a safe and orderly flow of air traffic. In uncontrolled airspace, normal rules of the air apply, for example, two aircraft meeting head on must both alter their heading to the right in order to both pass with the other aircraft on the left.
The actual "risk of collision" you are asking about, for someone flying in uncontrolled airspace, is incredibly small. One reason is that the amount of traffic in uncontrolled airspace is typically quite low, since authorities will most likely establish air traffic control for congested areas. Even in uncontrolled airspace, flight information service is provided in order to - among other things - prevent collisions. And collision avoidance systems, such as TCAS, will also help. Crucially, all aircraft have windows, and the pilots are trained to look out in order to see potential conflicting aircraft and react in time.

Microscopic.  The majority of GA midairs happen coming to or in the circuit/traffic pattern, and are almost always planes going the same general direction on converging tracks where one descends onto another that is in its blind spot.  On other words, the time to really get nervous and vigilant mid-air wise is approaching the airport, and the downwind-base-turn to final.
Not to say you don't have to watch carefully all the other times, just that if you are going to have bad luck, around the airport is the most likely place.


text:
Why are there many different approach lighting systems?
Why not just have only 2 or 3? What's the point of having such a number of different configurations? What's the practical application of each lighting scheme? I mean, do they really help pilots in a different kind of way?

(source)

I'm not sure if the source is supposed to show the image but it clearly says at the source that The image could not be loaded

The different systems generally have to do with ILS landings and the ability to have the runway in sight. As approach systems have gotten better and our understanding of flight mechanics and general operations has increased the need for different systems has evolved. As new requirements come out and new (generally lower) minimums are allowed different lighting requirements may accompany that but not all airports can always afford to install new lighting (and other related things) as such most regulations allow older systems to stay in place so long as the minimums remain.
In some cases airports simply don't have the physical land at the runway threshold to install larger/longer light systems. In some cases they need to do things like extend out into the ocean to install the lights.

Small private airports can't afford the huge light displays - runway edge lighting, runway end lighting, and PAPI are pretty common and not that costly.  Maybe taxiway lights if you're lucky. No ILS at the smaller airports either.  Access to land for installing the larger systems is also a problem.


text:
What are the rules for racing on airport runways?
What are the adverse affects of burnout rubber left on the runways for airplanes?

Are you talking about loose FOD chunks of rubber, or rubber embedded in the pavement? Your question and the title ask two different questions. The "rules" probably vary by airport and really doesn't have an answer.

http://racetherunway.com/ why not ask the organisers of this event? I've met some of them a few months ago, they were nice enough people.

How about landing on the raceway

The adverse effect is once the layer of rubber gets too thick it starts to degrade braking performance, especially wet braking because the rubber is filling in the surface irregularities that help channel water out from under the tire.  Aircraft wheels will hydroplane at much lower speeds and with less water depth.  Airports remove excess rubber from touchdown zones once it gets beyond a specified thickness.
I would expect that the rubber from spinning car tires would be no worse than the rubber that builds up on touchdown zones on heavily used runways.  If an airport is closing a runway to use for drag racing, it can't be a very busy airport, but in theory a really heavy rubber build up could be a concern if infrequent high performance aircraft like business jets use it, you know, when no drag racing is going on.  That would be up to the airport operator what to do about it.

which is precisely why runways are tested for traction regularly and cleaned as needed.


text:
What is the radius of a VOR compass rose on a VFR sectional chart?
I thought I read somewhere that it was 10 nautical miles. Does anyone have a reference on whether that's the case or not?
I'd like to use the measurement of a compass rose to aid in my estimation of how far away I might be from something else.

I measured one on a sectional and it came out to approximately 19.4 NM. However, as mentioned, I'm not sure it has a fixed size. Symbols on a map can be resized by the cartographers (map makers) for ease of reading. I would not rely on this for anything other than trivia.

https://aviation.stackexchange.com/a/24044/3159 suggests that the rose can be printed in a reduced size in congested areas, so it is not guaranteed to be a particular size.  Unfortunately I can't find the current copy of the specifications on the FAA site either through existing links or searching....
That said, the size mentioned in the quote (.75" in diameter) appears to be about a quarter of the size printed on a sectional.  So perhaps this is talking about another product.


text:
Where is this VFR reporting point ("Water Tank" near Thousand Oaks, CA) in real life?
I was looking at the VFR sectional near Thousand Oaks, California. The chart has a "WATER TANK" labeled, but I see many water tanks in Thousand Oaks on the Google Maps satellite view.
Does anyone know which water tank they are referring to on the sectional? And why would they choose something so easily confused with other "water tanks"?

(skyvector.com)

Google seems to match VPLWT with some coordinate. Does it match any actual water tank?

The tank is west of Oak Park (Oak Park Canyon), but there is some conflicting information about the exact coordinates of VPLWT.
From FAA JO 7350.8P:

34-10-49.0000N 118-46-16.0000W.

Converted into decimal degrees: 34.18028°N 118.7711°W

Google Maps
Obviously no tank here!
As @ymb pointed out, this document has been cancelled, and in the current version (JO 7350.9N), the coordinates have changed:

34-11-01.0000N 118-46-41.0000W.

Converted into decimal degrees: 34.18361°N 118.7781°W

Google Maps
An underground tank, well visible from the sky. The tank itself is likely similar to this (it may be it, but not sure):

"Local officials recently toured and inspected the new Oak Canyon water tank under construction in Oak Park", source
Other tanks
There are also two external tanks in the neighborhood, but none corresponds to FAA coordinates, e.g. this one:

Google Maps
which is a bit north of the underground tank. Overall picture:

Google Maps
It seems FAA has not done a good job about this waypoint identification. While the current source identifies a tank, it should be mentioned this tank is underground, as this makes a difference.


text:
What do the remarks of this metar mean? "RMK SC1SC5AC1 AC TR SLP116"
Here's the current METAR from CYYZ:
CYYZ 140700Z 26011KT 15SM FEW025 BKN045 BKN080 M05/M08 A2984 RMK SC1SC5AC1 AC TR SLP116
Does anyone know what each section of text of the remarks section means?

So the posted parts means the following:
  RMK    = REMARKS
  SC     = Stratocumulus Clouds
  1      = 1/8 (0/8 = no clouds / 8/8 = overcast clouds)`
  SC     = Again Stratocumulus Clouds
  5      = 5/8
  AC     = Altocumulus Clouds
  1      = 1/8
  AC TR  = Traces of Altocumulus
  SLP116 = Sea Level Pressure of 1011.6 mBar (just add a 10 before the given number and divide by 10)

Cloud Types:

Ac-Altocumulus
As-Altostratus
Cb-Cumulonimbus
Cc-Cirrocumulus
Ci-Cirrus
Cs-Cirrostratus
Cu-Cumulus
Fc-Fractocumulus
Fs-Fractostratus
Ns-Nimbostratus
Sc-Stratocumulus
St-Stratus

(Source: Wikipedia)
Octas:

(Source: Navcanada)

What's the difference between "completely overcast" and "sky completely obscured... by a phenomenon with a base not at the surface"?

@MichaelSeifert, I am not sure, but I suppose things like smoke (blowing across at some height) or volcanic ash would qualify. Basically something that looks like clouds, but is formed by something else than water condensation.

Isn't there a typo in the pressure? I believe SLP116 should mean 1011.6 hPa, not 1016 (which would be way too much for the 29.84 inHg; but then, 29.84 inHg is just 1010.5 hPa, not 1011.6)

@JanHudec of course! You're right, I fixed the number and added the explanation how it works. It's adding 10 in front and dividing by 10 to get the pressure in mBars.

The digit after the cloud layer type is the amount in oktas. See chapter "16.3.13.1 Layer type and amount (oktas)" in the canadian MANOBS Manual of Surface Weather Observations.
Amended 2019-02-16 to add:
Above manual also notes that the layer types and amounts in the RMK section correspond to the cloud layers aloft reported in the main section, and that the amount for layers aloft is reported as summation amount (as seen from the ground) while in the RMK section the amount is only for this layer, i.e. for your example:

FEW025: few clouds (1-2/8) ⇔ SC1: 1/8 stratocumulus
BKN045: broken layer (5-7/8) ⇔ SC5: 5/8 stratocumulus
BKN080: broken layer (5-7/8) ⇔ AC1: 1/8 altocumulus

To just decode the remarks you could also use metaf2xml with this link:

Remarks:
========
SC1SC5AC1  phenomenon w. opacity:
           1/8 (1/10) or less, but not 0/8 (0/10) stratocumulus
           5/8 (6/10) stratocumulus
           1/8 (1/10) or less, but not 0/8 (0/10) altocumulus
AC TR      traces of: altocumulus
SLP116     sea level pressure: 1011.6 hPa = 29.87 in. Hg = 759 mmHg


text:
Is a turbocharged piston aircraft the same thing as turboprop?
Simple question, and I've always assumed that they are the same thing, but I'd like feedback from someone who knows more than me :)

Definitely not-- important to know when you are adding fuel.  I'll let someone else take the honors of making a real answer!

No, just like a turbocharged car is not a jet/turboprop car

You might mind some interest in researching a Turbofan( big commercial airliner engine) vs turboprop(like a turbo fan but there is no outside cover for the main fan) vs a turbojet(fighter jet engine). A turbofan/prop use a jet engine to spin a very big blade to make thrust. A pure turbojet makes thrust just by the action of the jet itself no big propeller in front

@DeepSpace it's rather: “no, just like a turbocharged car is not a gas turbine car”. A jet or turboprop car would also have a different means of propulsion, whereas turboprops and turbo-supecharged pistons both have propellers which work essentially in the same way.

They are both internal combustion engines that have a turbine in their exhaust that is used to power a compressor to pressurize the air before it is used for combustion.
In the turboprop, the turbine also powers the prop.  In between the compressor and turbine, the fuel/air mixture is burnt without significant moving parts.  Without the turbine and compressor, a turbine engine is essentially a tube with heating element in it.
In a turbocharged piston engine, you have an otherwise normal piston engine which turns the prop.  The turbine is in the exhaust from the piston engine and powers the compressor pushing air into the piston engine.  The turbine and compressor are not connected to the prop though.
Here they are as diagrams along with some other types of engine.

Could note that "turbosupercharger" and "turbocharger" are often used interchangeably, while "supercharger" is sometimes used to mean "gear-driven supercharger" but really can mean either a gear-driven supercharger or a turbosupercharger (turbocharger).  I guess what I'm saying is that the diagram labelled "supercharger" would really be better labelled "gear-driven supercharger".  At least is the terminology that is most aligned with the original meaning of these words.  Maybe now "supercharger" is universally accepted to mean only the gear-driven variety? Could the basis of another question.

@quietflyer When researching engine stuff for.makimg an Xplane model I have íonly met "supercharchger" to mean the gear-driven one. It was for old engines, though.

@quietflyer I considered adding a note that "turbocharged" is also historically called "turbosupercharged" but the diagram was getting complicated enough as it was.  I thought that terminology was effectively dead but if it's still in use somewhere it would make sense to add.

Probably not a significant issue, see responses to my recently-posted related question.

No, a turboprop is more like a jet engine with a propeller in the front instead of a fan:

Source: Wikimedia

In its simplest form a turboprop consists of an intake, compressor, combustor, turbine, and a propelling nozzle. Air is drawn into the intake and compressed by the compressor.

Many turbo props have a gear box (as shown in the image above, the black part to the left) which drives the prop from the engine.
Whereas a turbo piston is simply a normal piston engine with a turbo charger attached:

Source: BoldMethod
You can learn more about how a turbo piston works on BoldMethod: How a turbocharger system works. The basics is that it uses the exhaust gases from the engine to drive a compressor which increases the pressure (and oxygen content) going into the intake. More oxygen (and fuel) means more power. For turbo-pistons it also means that you can get sea-level performance at altitude.
As far as fuel is concerned, a turboprop runs off of Jet-A (Kerosene) fuels and (most) turbo charged pistons run on av-gas. Some diesel turbo pistons also run off of Jet-A and it is very important that you don't put Jet-A in an av-gas piston or av-gas in a turbo prop.

"Some diesel turbo pistons also run off of Jet-A" -- which diesel turbo pistons don't run on Jet-A? is there another diesel fuel available at airports?

A turbocharged engine is a common gas engine with pistons

The limiting factor on a gas engine is how much air can get into the pistons.
It is supercharged - that is, an air pump forces more air into the engine than it would draw naturally. The mechanically driven variety is seen on Mad Max.  If you use exhaust flow to spin the pump, it is turbosupercharged.
People shorten "turbosupercharge" to "turbocharge".

A turboprop engine is a jet engine.  Fullstop.

The jet engine makes lots of thrust.  They stuck some extra turbine blades in the jet blast, which spin another shaft. That makes it a "turboshaft engine" because it makes rotation instead of thrust.  You put something useful on that shaft, like a generator, helicopter rotor, naval screw, air compressor, fan, propfan, or in this case, a prop.  That's a turboprop!

The advantage of a jet-based instead of piston-based engine is power-to-weight - after all you have nominally 2 moving parts, the spindle of the jet engine proper and the added turboshaft, and nothing reciprocates.

They are completely different things, a turboprop is similar to a jet engine as it has compressors, the main difference is that there's a shaft that spins a propeller instead of turning a fan.
A turbocharger is device for piston engines, it uses pressure coming from the exhaust manifold of a piston engine to compress air going into the intake manifold. It's the same technology used on car diesel and gasoline engines, and it works the same way. There are vanes that can be adjusted to manage the boost level, on cars these are computer controlled but in many airplanes turbo speeds are have to be manually adjusted by adjusting boost pressure in the exhaust (keyword: wastegate). Recent aero-diesels have modern computer controls though. Turbos on piston aero engines can either be turbochargers, in which case they add extra power to an engine by increasing the compression in the cylinders, or they can be turbo-normalizers, which maintain sea level air pressure to the engine even at higher altitudes.
There are superchargers as well, these are also compressors for piston engines the difference is they use engine power directly to compress the air rather than exhaust pressure.

I'd like the source for pilot controlled turbo vanes please... turbine housing vanes and wastegate are not the same thing. Both are used for regulating boost pressure, but in a very different way.

I didn't understand your comment at first, I have edited for clarity. I don't know of any manually controlled vanes, it's manual wastegate control.

That matches my reality :)

Probably the only thing today that will!

Well, they are not that completely different things. The turbocharger uses the same principle and has the same function as one spool of a turbine, making a turbocharged engine is kind of a hybrid between reciprocating and turbine engine.

Could note that "turbosupercharger" and "turbocharger" are often used interchangeably, while "supercharger" is sometimes used to mean "gear-driven supercharger" but really can mean either a gear-driven supercharger or a turbosupercharger (turbocharger).  I guess what I'm saying is that your use of  "supercharger" would really be better replaced by "gear-driven supercharger".  At least is the terminology that is most aligned with the original meaning of these words.  Maybe now "supercharger" is universally accepted to mean only the gear-driven variety?  Could be the basis of another question.

The term turbosupercharger was the original name for a turbocharger but fell out of use a long time ago @quietflyer. I haven't heard that term used except in historical context.

No, one is https://en.wikipedia.org/wiki/Otto_cycle one is https://en.wikipedia.org/wiki/Brayton_cycle, thermodynamicly extremely different

authors: Vladimir F Героям слава


text:
How does a departure off a runway used for LAHSO operations work?
Let's say that LAHSO operations are in effect at Long Beach (KLGB). Runway 12/30 has a hold short line short of runway 8L / 26R. If an aircraft is cleared to land runway 30, and LAHSO operations are in use, I get that.
But how do operations work for departures off of runways that have a hold short line painted on the runway? If an aircraft is cleared for takeoff runway 30, is the aircraft expected to disregard the hold short line at the departure end of the runway and use full-length?

Source: bing.com

For those of us not well-versed in acronyms: LAHSO - Land And Hold Short Operations

The same runway would be significantly shorter for takeoff than for landing, since a takeoff would not only need to be airborne by the LAHSO line, but also climb to a safe height to cross well above any crossing traffic


text:
Does transition to GBAS navigation require alignment of the intermediate segment with final segment?
I am studying how the Ground Based Augmentation System (GBAS) affects the Instrument Approach Procedures, and I noticed that in ICAO's Aircraft Operations manual (8168, Volume II) it states:

Part III, Section 3, Chapter 6, 6.3.2: "The intermediate approach segment of a GBAS procedure shall be aligned with the final approach course."

I would like to make sure if the rule concerning the alignment of the intermediate segment with the final segment implies that the whole segment (each leg of the intermediate segment) has to be aligned with the final, rather than only the last leg.
Could someone point me in the right direction?

I think this is close enough to your SBAS question that they could be combined.

I apologize for the inconvenience, since the question concerns different navigation system (GBAS instead of SBAS), I thought that it was appropriate to open a separate thread. But you are right, probably I should combine them. I will edit the other question to include the GBAS navigation system.


text:
Ambiguous mention of NAVAIDs with duplicate names in FAA's CIFP file (ARINC-424 18 format)
I am studying FAA's Coded Instrument Flight Procedures (CIFP) dataset (link), coded in ARINC-424 18 format, and I noticed that navaids are coded for the purposes of an IFP simulation only by their short name. The problem is, a number of navaids have duplicate names.
Take, for example, this sample from CIFP, describing ELMAA3 departure procedure:

It's impossible to distinguish if the VI leg during this departure procedure has to intercept a course beginning from either SEA VORTAC or SEA VOT. Both are near the airport but significantly far from each other.
Am I missing something? Perhaps only certain types of navaids are used? Could someone point me in the right direction?

A VOT is not a navaid.  It's a test signal generator for VOR receivers. The procedure intercepts the radial to the VORTAC.


text:
What are early/inside and late/outside turns (see, e.g., PBN Manual Order 8260.58A) and when do pilots perform them?
While studying FAA's PBN Manual (Order 8260.58A), I came across the concept of early/inside and late/outside turn construction (Section 5-3. Turning Departures).
For each of the possible cases, it provides instructions for constructing different Obstacle Clearance Areas.
Here are some examples:

a.) Early and inside turn construction
1. Turn following VA leg.
2. Turn follow VI leg.
3. Turn-at-fix (FO or FB).
b.) Late and outside turn construction
1. Wind spiral application

My question is, what are these kind of turns exactly? Are they special cases of a "normal" (expected) turn? In addition, how do pilots know when they have to perform such turns?
What also confuses me is the fact that the PBN manual, which describes the design of IFPs, covers such cases that have to do with a pilot's/ATC's "on the spot" decision. When designing, for example, a SID, shouldn't you end up with one (multi-branched or not) Departure Procedure, with specific waypoints selected after the evaluation of specific Obstacle Clearance Areas covering "normal" turns and not special cases?

I think what you're talking about are what pilots refer to as "fly-past" and "fly-over" waypoints.
Up until recently, all waypoints in the world were "fly-past", ie you could cut the corner from one leg to the next and not actually fly over the waypoint itself. This is still the standard, unless otherwise stated.
But then some SIDs and STARs needed people to actually fly OVER the waypoint before turning onto the next leg, and so coding was included in FMCs etc to get the autopilot to not start the turn until AFTER the waypoint. The difficulty is that there's usually not any differentiation in the presentation on the CDU between "fly-over" and "fly-past" - you have to look at the produced track on the ND to then see whether you're cutting the corner or turning after the waypoint.

thank you for your feeback but I am not talking about FB or FO waypoints. I am talking about different Obstacle Clearance Areas construction shortly after the Initial Climb Area, depending on an aircraft's "early" or "late" turn. What I am having trouble understanding is what early and late turns actually mean.


text:
How to accurately determine Navigation Accuracy from FAA's PBN Criteria (Order 8260.58A)?
I am trying to understand how to determine the Navigation Accuracy for a given flight phase of an Instrument Flight Procedure, from the US Standard for PBN Instrument Procedure Design (Order 8260.58A). However, I am unable to understand how to determine the aforementioned accuracy under certain circumstances, given that, for example in case of A-RNP navigational specification and STAR flight phase, it states that:

1-2-4.c, Table 1-2-1 A-RNP permits a range of scalable RNP lateral navigation accuracies. Apply the largest RNP for the flight phase unless a smaller value is required to achieve a desired ground track or is operationally required. RNP APCH applies to final flight phase.

My question is, in other words, why a desired ground track would require a smaller navigation accuracy value? Under what circumstances such a ground track would be desirable and, since the goal is to provide an adequate Obstacle Clearance Area, doesn't this mean that smaller accuracy value would lead to a smaller obstacle clearance area?
It is a really technical question and I do not expect to be a popular one, but I would really appreciate if someone could point me in the right direction.

Im more familiar with EASA then FAA but im sure there are similarities:
why a desired ground track would require a smaller navigation accuracy value?
RNP 2: the aircraft must be within ± 2 nm of the indicated position 95% of the flying time (Required for Basic RNAV).
RNP 1: the aircraft must be within ± 1 nm of the indicated position 95% of the flying time (Required for Precision RNAV).
So flying in a congested airspace (for example the NAT-OTS routes) ATC can accommodate more aircraft with smaller separations.
the goal is to provide an adequate Obstacle Clearance Area
Yes, as well as separation and spacing of aircraft.
doesn't this mean that smaller accuracy value would lead to a smaller obstacle clearance area?
In theory yes. But Obstacle clearance requirements around Airports and high terrain take into account all aircrafts including general aviation and older aircraft without PBN, RNP equipment so while you are right with more accuracy the approach and departure corridors lead to smaller clearance areas due to the regulations the actual clearance areas could stay the same.
More likely there will be changes at the approach and departure procedures (points, fixes and routes).
Hopefully you found something helpful.